Systems that support online services, such as internet banking, receive many inputs from computer users interacting with an online service. For example, an online banking service that provides a website to account holders may receive many mouse clicks, or web clicks, or key strokes over the course of a single online banking session. Each of the individual clicks or strokes represents a discrete event. There may be a pattern to a sequence of clicks in a single online banking session, and this pattern may reveal information about the source of the clicks. Specifically, a periodic set of clicks may raise concerns that the source of the clicks is a threat, such as a password cracker program.
Conventional online support services detect periodicity in a sequence of clicks by using algorithms that seek out equally spaced clicks via direct measurement, or by other means such as Fourier transforms.